Work · Analytic Philosophy
Studies in the Logic of Confirmation
If every black raven confirms “all ravens are black”, then so does every non-black thing that is not a raven – a white shoe, as later retellings put it: the paradox of confirmation.
Introduction
Carl Gustav Hempel, who had studied with Hans Reichenbach in Berlin and emigrated in the 1930s, published this two-part paper in Mind in 1945. He asks what it means for an observation report to confirm a general hypothesis, and examines conditions such as Nicod’s criterion – an A that is B confirms “all A are B” – and the equivalence condition, according to which whatever confirms a hypothesis also confirms every logically equivalent one. Together they produce the paradox: “all ravens are black” is equivalent to “all non-black things are non-ravens”, so any non-black non-raven confirms it. Hempel accepts the conclusion and explains the sense of paradox by the background knowledge we tacitly bring in. The paradox is still discussed.
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